The purpose of the Analytical Core is to provide support to Center investigators for the structural and quantitative analysis of eicosanoids. Assay methodology based on capillary column gas chromatography/electron capture negative ion chemical ionization mass spectrometry will be available for high sensitivity quantitative analyses. Lower sensitivity assays will be carried out using gas chromatography/electron ionization mass spectrometry. Structural analyses will be carried out on one of the eight mass spectrometers that are available in the Core. Ionization techniques that are available include, fast atom bombardment, thermospray, electrospray and desorption chemical ionization. We propose to develop new methods for eicosanoid analysis based on capillary HPLC in combination with electrospray mass spectrometry. In addition, we propose to explore the use of a new four- sector tandem mass spectrometer for carrying out the structural elucidation of novel eicosanoids. Of particular interest will be the coupling of high resolution electrospray ionization with the high energy collision regime that is available on the four sector instrument. The quadrupole instruments will also be available to individual investigators should they want to carry out their own analyses. Investigators will be trained in instrument operation when necessary. Advice on the use of appropriate ionization techniques and column selection will be provided by personnel in the Core. The Core will also provide a resource for the synthesis of eicosanoid metabolites and stable isotope standards for use in stable isotope dilution assays. Structural confirmation of new metabolites will be carried out by chemical synthesis.